Date of incident: June 2020
Notice of incident number: 2020173460003
Employers: Trucking companies (2); wood‑frame construction company

Incident summary
A worker was using a crane truck to unload a delivery of lumber onto a temporary structure (deck) at a house under construction. As the worker was moving the last of the lumber, the deck collapsed, and debris from the collapse struck and injured him.

Investigation conclusions

Cause

• Heavy load caused deck to collapse. The deck already had materials stacked on it. These materials weighed approximately 1114 kg. The materials that the worker placed on it from the crane truck weighed approximately 5741 kg. The deck was not capable of supporting that much weight, and so it collapsed.

Contributing factors

• Inadequate planning. The wood‑frame construction employer failed to consider lateral stability in the design of the temporary structure (the deck). The employer also failed to have the design for the deck reviewed or approved by an engineer. No calculations or other types of assessments were done to determine how much weight the deck could hold. When the deck was being built, the employer did not ensure that the manufacturer’s instructions for installing hangers in the columns supporting the deck were followed. The employer also did not ensure that access to the unfinished deck was restricted so as to prevent workers from overloading the deck prior to its completion.
• Lack of hazard identification and safe work procedures. The wood‑frame construction employer failed to develop an engineered plan or equivalent design for the construction of a temporary structure (the deck) that could withstand the loads applied to it. This created a hazard to workers, as the deck’s load capacity was unknown. This hazard was not identified by the wood‑frame construction employer nor communicated to the worker delivering the lumber. Neither the firm that owned the crane truck nor the trucking firm that subcontracted the delivery job to that firm made adequate inquiries as to the unloading area’s structural integrity. There were no written instructions or clear communications on where to place the materials, nor any safe work procedures for the unloading task.
• Prime contractor failed to coordinate activities at worksite. The prime contractor (the wood‑frame construction employer) had no system in place for coordination of work at the multi‑employer workplace. Information regarding the unfinished temporary structure (the deck) was not adequately communicated to employers and workers to prevent overloading it. This allowed conditions to develop at the worksite that put the health and safety of workers at risk.

Request the full report